Rotor mold



Feb. 24, 1931. 1 c. E JQHNSON 1,793,855

ROTOR MOLD Filed Feb. 18, 1929 flTToen/Ey Patented Feb. 24, 1931 UNlTEDSTATES PATENT OFF-WE CARL E. JOHNSON, OF PASADENA, CALIFORNIA,ASSIGNOR'TO STERLING ELECTRIC MOTORS, INCL, OF LOS ANGELES, CALIFORNIA,A CORPORATION OF CALIFORNIA ROTOR MOLD Application filed February 18,1929. Serial No. 340,991.

' lar utility in casting rotors, for instance, or

other devices.

Such devices are ordinarily singly cast 1n a mold from which they aresubsequently removed. Machining is invariably necessary.

I have invented a mold whereby a plurality of rotors or other elementsmay be simultaneously cast, thus effecting a great saving in time aswell as making possible a continuous process whereby a mold may beutilized time after time without preheating or supplying thereto anyexternal heat other than that received from the molten metal. I

It'is an object of this invention to provide a mold. whereby a pluralityof elements may be cast at the same time.

Still. a further object of this invention is to provide a mold having acasting chamber and a pouring chamber whereby the molten substance maybepoured into the pouring chamber and may pass into the casting chamber atthe lower end thereof. This metal then rises to fill a casting chamberto form the element so that no subsequent machining is necessary.

A further object of this invention is to provide a mold whereby thecontraction of the cooling metal is compensated for so that thiscontraction will not cause undue strains in the cast element.

A further object of this invention is to provide a novel method ofcasting rotors or other elements.

Still further objects and advantages of this invention will be madeevident hereinafter.

Referring to the drawing,

Fig. 1 is a vertical cross-sectional view of my invention showing theform thereof utilized for casting rotors, one .of these rotors beingshown as cast, and the other being shown as it a pears after theprotruding tongues are file 05.

Fig.- 2 is a plan view, partly in'section, of my invention shown insection Fig. 1.

Referring particularly to Fig. 1, my in vention comprises a confiningmember 10 having a base 11 and side walls 12. This member is preferablyformed in the shape of a cloverleaf, as shown in Fig. 2, and provides aplurality of chambers 13 positioned therearound. It is ordinarilypreferable to form these chambers so that the walls thereof diverge veryslightly in an upward direction. The construction of the confiningmember 10 is best shown in Fig. 2, which clearly indicates both theshape and position of the chambers 13 in the confining member 10.

The walls 12 provide webs 14 separating adjacent chambers 13, these websterminating in arcuate walls 15, each of which is formed on an equalradius of the vertical axis of the confining member 10 indicated by thenumeral 16.

Adaptedto engage the arcuate walls 15. and to be centrally disposedrelative to the confining member 10, is a core member 18 whichcooperates with the confining member 10 in defining the chambers 13. theouter pcripliery of the core member having out therein channels 19, theradius of curvature of which is the same as the radius of curvature ofthe chamber 13, these channels being positioned so as to lie between thepoints of the webs 14 in a manner to form the chambers Adapted to fit ineach of the chambers 13 IS a core element 20. In the particular formshown this core element comprises a base plate 21 which rests on thebase 11 ot the confining mcmber and has an arbor 22 extend ing upwardand around which rotor laminations 23 are placed. A cap2l isthen placedover the arbor 22 and forced downward by means of an eyebolt 25 having ahead 26 hearing against the cap 24-, and a screw 27 threaded into thearbor 22, so as to clamp the laminations between the base plate and thiscap. It should be understood that the core elements 20 are assembledbefore being inserted in the chambers 13.

The walls of the chambers 13 provide shelves 35 which cooperate with thebase plate 21 in forming a s ace for a lower end ring 36 of the rotor.imilary, the cap 2-1 provides an annular channel 37 wherein is formed anupper end ring 38. The laminations 23 have notches 39 cut therein whichare brought into alignment when these laminations are assembled on thearbor 22, these notches providing spaces for forming conductor bars 40.These conductors bars,

and the end rings 36 and 38 are cast integrally in place by molten metalwhich is poured into a pouring chamber 43' formed in the core member 18,this metal passing through passages 44, one of which communicates withthe lower end of each chamber 13. lhe space in the chamber 13 which isfilled by the molten metal entering the lower end thereof has beentermed a casting chamber and is indicated by the numeral 45, thischamber being defined below the cap 24 and inside the walls 12.

'lhis methodof casting rotors by pouring a molten metal into the lowerend of a casting chamber is a very important part of this invention.There is, of course, a tendency for the molten liquid to maintain thesame level in the pouring chamber 43 as it does in the casting chamber45 so that as the level of the molten metal in the pouring chamberbuilds up, this molten metal passes through the passages 44 andsimultaneously fills each of the casting chambers to substantially thesame level.

Molten metal is poured into the pouring chamber 43 until it reaches alevel 48 above the uppermost portion of the casting chamber 45. Themolten liquid in the casting chamber is thus subjected to a pressure,and any contraction of the molten metal in the casting chamber will becompensated for by a renewed supply of molten metal through the passages44. The amount of metal passing through the passages 44 after thecasting chamber has been filled is, of course, small due to the factthat the shrinkage is not large. As soon as the metal in the castingchamber sets no further flow can, of course, take place. but I havefound that this method of casting produces rotors which show little orno shrinkage effects. It should be understood that the metal in thepouring chamber 43 remains molten after the metal of the casting chamberhas been set, due to the central placing of this pouring chamber. Thisinsures a supply of molten metal to the passages 44 which may enter thecasting chamber 45 and compensate for contraction of the cooling metaltherein.

As the level of the molten liquid in the casting chambers rises, the airentrapped thereabove, is vented to the atmosphere through a vent meansin the form of three small openings 47 formed through the cap 24 andcommunicatingwith the casting chamber 45. Any molten metal which risesin these openings may be easily chipped off. but I have found by makingthese openings sufiiciently small that there is little tendency for themolten metal to rise therein.

When the metal in the casting chamber has greases hardened, asuitable'means is utilized for $11- gaging each of the eye-bolts 25 insuch a manner-that the filled mold and its associated rotors issuspended therefrom. The confining member 10 is then tapped, and thismember drops, leaving the core member secured to the rotor by means ofthe metal filling the passages 44. The core member 18 is then tapped atthe bottom in a manner to remove this core member from engagement withthe rotors which are still secured together and v to the metalpreviously in the pouring chamber 43 by means of the metal previouslyfilling the passage 44. These latter portions of metal are then suitablycut, and the rotor removed from between the base plate 21 and cap 24after the eyebolt 25 has been unscrewed. The rotor is completed in thisform with the exception that itis, of course, necessary to remove themetal previously occupying the passages 44 and the o enings 47 thisbeing conveniently done by filing or grindmg.

In the right-hand side of Fig. 1 I have shown the completed rotor in thecasting chamber 45, while on the left-hand side of this figure is showna rotor in the process of being formed and having attached thereto thematerial in the passage 44: It should thus be apparent that no expensivemachine operations are necessary on the completed rotor, the only worknecessary being that of filing oil the metal protrusions, as previouslyexplained. v

urthermore, it is not necessary to preheat the mold except when thefirst batch of rotors is being cast. Subsequently, the rotors areremoved before the confining member 10 and core member 18 are cold, thuspermitting additional rotors to be poured without preheating thesemembers. -T his continuous process is a saving not only in the heatunits previously required in preheating the mold, but also permits onemold to be used continuously, thus performing the work previously doneby a large number of molds.

it should further be understood that my invention is not limited to aconfining member of the clover-leaf shape shown. Such a shape is used onsmall rotors, but on larger sized rotors it is preferable to decreasethe number ofcasting chambers formed around the pouring chamber 43, andwith rotors of very large size it is desirable to utilize a singlecasting chamber in conjunction with the pouring chamber 43. All of theseforms fall within the scope of this invention.

Furthermore, while I have shown and described my invention as beingapplied to motors for induction machinery, such a use is not essentialto the utility thereof. It is possible to cast various other articles inmy mold, including pistons or other metallic or non-metallic bodies.

A very important feature of this invention end thereof; and vent meansin is the method of introducing a molten substance into the lower end ofa casting chamber, and venting the upper end of this chamber to permitthe escape of gases therefrom. This system finds its maximum utilitywhen the walls of the pouring chamber extend above the walls of thecasting chamber whereby a pressure-head may be maintained on the moltenmaterial in the casting chamber.

I claim as my invention:

1. A mold comprising: walls defining a plurality of casting chambers;walls forming a pouring chamber around which said casting chambers areplaced, said casting chambers and said pouring chamber being separatedby but a single wall; and means communicating between said pouringchamber and the lower portion of each of said casting chambers.

2. A mold comprising: a confining member; a core member removablypositioned in said confining member and having a pouring chambertherein, said core member cooperating with said confining member todefine a chamber; and means communicating between said chamber and saidpouring chamber in a manner to conduct a molten substance thereto.

3. A rotor mold comprising: walls defining a casting chamber; means forsupporting a group of laminations in said casting chamber, said meansextending substantially across said casting chambers; walls defining asa unit together with the casting material. 70 In testimony whereof, Ihave hereunto set my hand at Los Angeles, California, this 13th day ofFebruary, 1929.

CARL E. JOHNSON.

a pouring chamber adjacent said casting I chamber and communicating withthe lower said means for venting said casting chamber.

4. A mold comprising: a confining member providing a plurality of websextending inward; and a core member removably positioned in saidconfining member and defining a central pouring chamber, said coremember cooperating with said webs in defining a plurality of chambersgrouped around said pouring chamber and communicating therewith.

5. A combination as defined in claim 4 in which the ends of said websare in the form of arcuate walls, and in which said core member providesan outer face corresponding in curvature to said arcuate walls andengaging therewith.

6. A combination as defined in claim 4 in which said core memberprovides channels corresponding in curvature to said chambers andforming a continuation of the walls of said chambers.

7. A mold comprising: a confining member; a core member removablypositioned in said confining member and having a pouring chambertherein, said core member cooperating with said confining member todefine a plurality of chambers around sald pourmg chamber and incommunication therewith; a core element positioned 1 each of said cham-

